Interference from nonlocal double-slit with pseudo-thermal light

We perform an interference experiment in which a pseudo-thermal light beam illuminates two spatially separated apertures, whose superposition at the same place forms a double-slit. The experimental result exhibits a typical double-slit interference fringe in the intensity correlation measurement, in agreement with the theoretical analysis by means of the property of the second-order spatial correlation of field of the thermal light.     

Improving Visibility of Diffraction Pattern with Pseudo-Thermal Light

We report an experimental observation of Poisson＇s spot with pseudo-thermal light. The experimental results show that the diffraction pattern disappears in the intensity distribution behind the opaque disc but emerges through both auto-correlation and cross-correlation intensity measurements. The auto-correlation scheme can take care of both better visibility and higher resolution of the diffraction pattern under the condition that the thermal light source has a larger spectral bandwidth.     

Effect of high temperature band gap of GaN annealing on strain and nanoparticles

<正>Black-coloured GaN nanoparticles with an average grain size of 50 nm have been obtained by annealing GaN nanoparticles under flowing nitrogen at 1200℃for 30 min.XRD measurement result indicates an increase in the lattice parameter of the GaN nanoparticles annealed at 1200℃,and HRTEM image shows that the increase cannot be ascribed to other ions in the interstitial positions.If the as-synthesised GaN nanoparticles at 950℃are regarded as standard,the thermal expansion changes nonlinearly with temperature and is anisotropic;the expansion below 1000℃is smaller than that above 1000℃.This study provides an experimental demonstration for selecting the proper annealing temperature of GaN.In addition,a large blueshift in optical bandgap of the annealed GaN nanoparticles at 1200℃is observed,which can be ascribed to the dominant transitions from the C（Γ₇） with the peak energy at 3.532 eV.     

Modeling process of the neutral beam re-ionization loss

The basic process of re-ionization loss was studied.In the drift duct there are three processes leading to re-ionization loss：the collision of neutral beam particles with the molecules of background gas,similar collisions with released molecules from the inner wall of the drift duct and the ferret-collisions among particles with different energy of the neutral beam.Mathematical models have been developed and taking EAST-NBI parameters as an example,the re-ionization loss was obtained within these models.The result indicated that in the early stage of the neutral beam injector operation the released gas was quite abundant.The amount of re-ionization loss owing to the released gas can be as high as 60%.In the case of a long-time operation of the neutral beam injector,the total re-ionization loss decreases from 13.7% to 5.7%.Then the reionization loss originating mainly from the collisions between particles of the neutral beam and the background molecules is dominant,covering about 92% of the total re-ionization loss.The drift duct pressure was the decisive factor for neutral beam re-ionization loss.     

Influences of anionic and cationic dopants on the morphology and optical properties of PbS nanostructures

Selenium and zinc are used as anionic and cationic dopant elements to dope PbS nanostructures. The undoped and doped PbS nanostructures are grown using a thermal evaporation method. Scanning electron microscopy （SEM） results show similar morphologies for the undoped and doped PbS nanostructures. X-ray diffraction （XRD） patterns of three sets of the nanostructures indicate that these nanostructures each have a PbS structure with a cubic phase. Evidence of dopant incorporation is demonstrated by X-ray photoelectron spectroscopy （XPS）. Raman spectra of the synthesized samples con- firm the XRD results and indicate five Raman active modes, which relate to the PbS cubic phase for all the nanostructures. Room temperature photoluminescence （PL） and UV-Vis spectrometers are used to study optical properties of the undoped and doped PbS nanostructures. Optical characterization shows that emission and absorption peaks are in the infrared （IR） region of the electromagnetic spectrum for all PbS nanostructures. In addition, the optical studies of the doped PbS nanos- tructures reveal that the band gap of the Se-doped PbS is smaller, and the band gap of the Zn-doped PbS is bigger than the band gap of the undoped PbS nanostructures.     

Improved Ligand-Field Theoretical Calculations of R-Line Thermal Broadenings of NIgO：Cr^3＋ and MgO：V^2＋

With the values of parameters obtained from improved ligand-field theory, by taking into account all the irreducible representations and their components in EPI as well as all the levels and the admixtures of basic wavefunctions within d^3 electronic configuration, the R-line thermal broadenings （TB） of both MgO：Cr^3＋ and MgO：V^2＋ have microscopic-theoretically been calculated, The results are in very good agreement with the experimental data. It is found that the R-line TB of MgO：Cr^3＋ or MgO：V^2＋ comes from the first-order term of EPI. The elastic Raman scattering of acoustic phonons plays a dominant role in R-line TB of MgO：Cr^3＋ or MgO：V^2＋.     

Energy Spectrum,g Factors,Strain-Induced Level-Splittings and R-Line Thermal Shift of MgO：V^2＋＋

Traditional ligand-field theory has to be improved by taking into account both pure electronic contribution and electron-phonon interaction one （including lattice-vibrational relaxation energy）. By means of improved ligand-field theory, the R line, t^322T1 and t^322T2 lines, t^22（^3T1）e^4T2, t^22（^3T1）e^4T1 and t2e^2（^4A2）4T1 bands, g factors of t^32 ^4A2 and t32E, four strain-induced level-splittings and R-line thermal shift of MgO：V^2＋ have been calculated. The results are in very good agreement with the experimental data. It is found that for MgO：V^2＋, the contributions due to electronphonon interaction （EPI） come from the first-order term; the contributions from the second-order and higher terms are insignificant. In thermal shift of R line of MgO：V^2＋, the temperature-dependent contribution due to EPI is dominant. The results obtained in this work may be used in theoretical calculations of other effects of EPI.     

Cooling of Akmal-Pandharipande-Ravenhall neutron stars with a rotochemical heating source

Employing phenomenological density-dependent critical temperatures of strong singlet-state proton pairing and of moderate triplet-state neutron pairing, we investigate the effects of rotochemical heating on the thermal evolution of superfluid neutron stars whose cores consist of npe matter with the Akmal-Pandharipande-Ravenhall equation of state. Since the star is not quite in the weak interaction equilibrium state during spin-down, the departure from the chemical equilibrium leads to the rotochemical heating in a rotating NS which will increase the stellar＇s temperature. Our calculations show that the rotochemical heating delays the cooling of superfluid neutron stars considerably and makes the previous classification of NS cooling ambiguous. What＇s more, our model is currently consistent with all the observational data, and in particular some middle-aged and cold NSs （PRS J0205＋6449 in 3C 58, PRS J1357-6429, RX J007.0＋7303 in CTA 1, Vela） can be better explained when taking into account rotochemical heating.     

Fabrication of VO_2 thin film by rapid thermal annealing in oxygen atmosphere and its metal–insulator phase transition properties

Vanadium dioxide thin films have been fabricated through sputtering vanadium thin films and rapid thermal annealing in oxygen. The microstructure and the metal–insulator transition properties of the vanadium dioxide thin films were investigated by X-ray diffraction, X-ray photoelectron spectroscopy, and a spectrometer. It is found that the preferred orientation of the vanadium dioxide changes from(1ˉ11) to(011) with increasing thickness of the vanadium thin film after rapid thermal annealing. The vanadium dioxide thin films exhibit an obvious metal–insulator transition with increasing temperature, and the phase transition temperature decreases as the film thickness increases. The transition shows hysteretic behaviors, and the hysteresis width decreases as the film thickness increases due to the higher concentration carriers resulted from the uncompleted lattice. The fabrication of vanadium dioxide thin films with higher concentration carriers will facilitate the nature study of the metal–insulator transition.     

Speckle intensity images of target based on Monte Carlo method

Speckle intensity in the detector plane is deduced in the free-space optical system and imaging system based on Van Cittert-Zemike theorem. The speckle intensity images of plane target and conical target are obtained by using the Monte Carlo method and measured experimentally. The results show that when the range extent of target is smaller, the speckle size along the same direction become longer, and the speckle size increase with increasing incident light wavelengths. The speckle size increases and the speckle intensity images of target is closer to the actual object when the aperture scale augments. These findings are useful to access the target information by speckle in laser radar systems.     

Phase transformation in Mg Sb_3Te thin films

Mg-doped Sb3Te films are proposed to improve the performance of phase-change memory （PCM）. We prepare Mg- doped Sb3Te films and investigate their crystallization behaviors, structural, optical and electrical properties. We find that Mg-doping can increase the crystallization temperature, enhance the activation energy, and improve the 10-year data retention of Sb3Te. Especially Mg25.19（Sb3Te）74.81 shows higher Tc （~ 190℃） and larger Ea （~ 3.49 eV）, which results in a better data retention maintaining for 10 yr at ~ 112 ℃. Moreover Ra/Rc value is also improved. These excellent properties make Mg-Sb-Te material a promising candidate for the phase-change memory （PCM）.     

Stochastic resonance in an over-damped linear oscillator

For an over-damped linear system subjected to both parametric excitation of colored noise and external excitation of periodically modulated noise, and in the case that the cross-correlation intensity between noises is a time-periodic function,we study the stochastic resonance(SR) in this paper. Using the Shapiro–Loginov formula, we acquire the exact expressions of the first-order and the second-order moments. By the stochastic averaging method, we obtain the analytical expression of the output signal-to-noise ratio(SNR). Meanwhile, we discuss the evolutions of the SNR with the signal frequency, noise intensity, correlation rate of noise, time period, and modulation frequency. We find a new bona fide SR. The evolution of the SNR with the signal frequency presents periodic oscillation, which is not observed in a conventional linear system. We obtain the conventional SR of the SNR with the noise intensity and the correlation rate of noise. We also obtain the SR in a wide sense, in which the evolution of the SNR with time period modulation frequency presents periodic oscillation. We find that the time-periodic modulation of the cross-correlation intensity between noises diversifies the stochastic resonance phenomena and makes this system possess richer dynamic behaviors.     

Performance characteristics a nonlinear diode and optimal analysis of refrigerator

This paper establishes a model of a nonlinear diode refrigerator consisting of two diodes switched in the opposite directions and located in two heat reservoirs with different temperatures. Based on the theory of thermal fluctuations, the expressions of the heat flux absorbed from the heat reservoirs are derived. After the heat leak between the two reservoirs is considered, the cooling rate and the coefficient of performance are obtained analytically. The influence of the heat leak and the temperature ratio on the performance characteristics of the refrigerator is analysed in detail.     

Thermal modeling optimization and experimental validation for a single, concentrator solar cell system with a heat sink

A single concentrator solar cell model with a heat sink is established to simulate the thermal performance of the system by varying the number, height, and thickness of fins, the base thickness and thermal resistance of the thermal conductive adhesive. Influence disciplines of those parameters on temperatures of the solar cell and heat sink are obtained. With optimized number, height and thickness of fins, and the thickness values of base of 8, 1.4 cm, 1.5 mm, and 2 mm, the lowest temperatures of the solar cell and heat sink are 41.7℃ and 36.3℃ respectively. A concentrator solar cell prototype with a heat sink fabricated based on the simulation optimized structure is built. Outdoor temperatures of the prototype are tested. Temperatures of the solar cell and heat sink are stabilized with time continuing at about 37℃-38℃ and 35℃-36℃ respectively, slightly lower than the simulation results because of effects of the wind and cloud. Thus the simulation model enables to predict the thermal performance of the system, and the simulation results can be a reference for designing heat sinks in the field of single concentrator solar cells.     

Characterizing a proton beam with two different methods in beam halo experiments

In beam halo experiments, it is very important to correctly characterize the RFQ output proton beam. In order to simulate the beam dynamics properly, we must first know the correct initial beam parameters. We have used two different methods, quadrupole scans and multi-wire scanners to determine the transverse phase-space properties of the proton beam. The experimental data were analyzed by fitting to the 3-D nonlinear simulation code IMPACT. For the quadrupole scan method, we found that the RMS beam radius and the measured beam-core profiles agreed very well with the simulations. For the multi-wire scanner method, we choose the case of a matched beam. By fitting the IMPACT simulation results to the measured data, we obtained the Courant-Snyder parameters and the emittance of the beam. The difference between the two methods is about eight percent, which is acceptable in our experiments.     

Application of thermal stress model to paint removal by Q-switched Nd:YAG laser

In this paper, we demonstrate that thermal stress is the main mechanism in the process of paint removal by Q-switched Nd：YAG laser （λ = 1064 nm, τ = 10 ns）. A theoretical model ofpaint removal by short-pulse laser is established from the perspective of thermal stress. Thermal stress is generated by thermal expansion, and the temperatures of different samples are calculated according to the one-dimensional （1D） heat conduction equation. The theoretical cleaning threshold can be obtained by comparing thermal stress with the adhesion of paint, and the theoretical damage threshold is obtained by calculating the temperature. Moreover, the theoretical calculations are verified by experimental results. It is shown that the thermal stress model of the laser cleaning is very useful to choose the appropriate laser fluence in the practical applications of paint removal by Q-switched Nd： YAG laser because our model can validly balance the efficiency of laser cleaning and the safety of the substrate.     

Effects of Different Spin-Spin Couplings and Magnetic Fields on Thermal Entanglement in Heisenberg XYZ Chain

The effects of spin-spin interaction on thermed entanglement of a two-qubit Heisenberg XYZ model with different inhomogeneous magnetic fields are investigated. It is shown that the entanglement is dependent on the spin-spin interaction and the inhomogeneous magnetic fields. The larger the Ji （i-axis spin-spin interaction）, the higher critical value the Bi （i-axis uniform magnetic field） has. Moreover, in the weak-field regime, the larger Ji corresponds to more entanglement, while in the strong-field regime, different Ji correspond to the same entanglement. In addition, it is found that with the increase of Ji, the concurrence can approach the maximum value more rapidly for the smaller Bi, and can reach a larger value for the smaller bi （i-axis nonuniform magnetic field）. So we can get more entanglement by increasing the spin-spin interaction Ji, or by decreasing the uniform magnetic field Bi and the nonuniform magnetic field hi.     

Thermal transport property of investigated by molecular Ge34 and d-Ge dynamics and the Slack＇s equation

In this study, we evaluate the values of lattice thermal conductivity κL of type Ⅱ Ge clathrate （Ge34） and diamond phase Ge crystal （d-Ce） with the equilibrium molecular dynamics （EMD） method and the Slack＇s equation. The key parameters of the Slack＇s equation are derived from the thermodynamic properties obtained from the lattice dynamics （LD） calculations. The empirical Tersoff＇s potential is used in both EMD and LD simulations. The thermal conductivities of d-Ge calculated by both methods are in accordance with the experimental values. The predictions of the Slack＇s equation are consistent with the EMD results above 250 K for both Ge34 and d-Ge. In a temperature range of 200-1000 K, the κL value of d-Ge is about several times larger than that of Ge34.     

Anti-plane problem analysis for icosahedral quasicrystals under shear loadings

The present paper is concerned with the longitudinal shear elasticity of three-dimensional icosahedral quasicrystals. By virtue of the Dugdale hypothesis along with the method of complex potential theory, it involves two defect problems of the icosahedral quasicrystals. The first one is the calculation of stress intensity factors and the size of the cohesive force zone in a half-infinite crack. Meanwhile, the crack tip tearing displacements can be exactly derived. The other is the demonstration of the generalized stress intensity factors induced by a sharp V-notch as an extension of a crack. The generalized E-integral around the notch tip gives the energy release rate when the V-notch degenerates into a crack. Apart from their own usefulness in carrying out some simplified crack analyses, the results obtained in this work can particularly serve as a basis for fracture mechanics of anti-plane defect problems of icosahedral quasicrystals.     

Thermal analysis for the high duty cycle PIMS accelerator

To develop the high power proton linear accelerator for the Accelerator Driven System（ADS） program,the preliminary design of the Pi mode accelerating structure（PIMS） has been carried out.It is estimated that PIMS would heat up to 80 for low duty cycle（0.1%） without water-cooling,which is not acceptable thus water-cooling is demanded.The structure stability for the high duty cycle or even for CW operation is crucially important for the ADS application.Therefore,thermal analysis with water-cooling for a high duty accelerator in our ADS research is performed to control the frequency shift caused by a temperature rise.